On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark
wrote:

On Thu, 25 Sep 2003 06:45:29 -0400, wrote:

Let's just all go metric. The only really confusing measure
there seems to be the definition of the litre.

...Keith

Hi Keith,

You mean liter? ;-)

Up there in the Great White North, they use those dinky little
"litres" where it takes 4.54609 of them to make a gallon, rather than
the man-sized liters we have, which only take 3.785411784 to make a
gallon. ;-)

Unless, of course, you are talking about blueberries, where we use an
inbetween liter where it takes 4.40488377086 liters to make a gallon
(which we actually don't use much under that name any more, though we
do still use its quart and pint subdivisions).

Gene Nygaard

"Fundamentals of Physics", Haliday and Resnick, Second Edition, 1981

Appendix F, Conversion Factors

Mass

"Quantities in the colored areas [ounce, pound, ton] are not mass units
but are often used as such. When we write, for example 1 kg "=" 2.205
lb this means that a kilogram is a _mass_ that _weighs_ 2.205 pounds
under standard condition of gravity (g = 9.80665 m/s^2)."

The units dyne, Newton, pound, and poundal are listed elsewhere in
Appendix F as units of force.

73, AC6XG

Gene Nygaard wrote:

On Thu, 25 Sep 2003 12:13:47 GMT, Dave Shrader
wrote:

Gene, thanks for the compliment in calling the Program Chief Engineer
of the USAF MX [Peacekeeper] Re-Entry System/Re-Entry Vehicle a fool.

It says a lot about you. I forgive you.

Dave, W1MCE
+ + +

Gene Nygaard wrote:
not concerned enough about the possibility that fools like you

Since you aren't honest enough to tell us exactly what Sears and
Zemansky said in 1956, I'll tell everyone what they said in 1970. If
there are any significant differences, feel free to point them out.
This thing is, I know that Sears and Zemansky weren't going to lie
about this, because they grew up using poundals, which are by
definition the force which will accelerate a MASS of 1 lb at a rate of
1 ft/s².

Francis Weston Sears and Mark W. Zemansky, University Physics,
Addison-Wesley, 4th ed., 1970.

[page 3]

1 pound mass = 1 lbm = 0.45359237 kg

[The actual number will, of course, be different in 1956, because the
U.S. didn't adopt this definition until 1959 (it had been in use in
Canada since 1953, six years before the international
redefinition).--GAN]

[page 4]

We select as a standard body the standard pound,
defined in section 1-2 as a certain fraction
(approximately 0.454) of a standard kilogram.

[page 59]

In setting up the mks and cgs systems, we first selected
units of mass and acceleration, and defined the unit of
force in terms of these. In the British engineering system,
we first select a unit of force (1 lb) and a unit of
acceleration (1 ft s^-2) and then define the unit of mass as
the mass of a body whose acceleration is 1 ft s^-2 when
the resultant force on the body is 1 lb.

end quote

Now, Sears and Zemansky might be incompetent for not allowing for the
fact that there are going to be people out there who are too blamed
stupid to understand that that adjectival phrase "British engineering"
has some meaning, and that it identifies one particular limited subset
of the British units. It's perhaps even understandable, because that
fact would be quite clear to anyone who, like them, had grown up using
poundals in a "British absolute" system of units.

However, that doesn't change the fact that you are in fact one of the
people who are that stupid.

--
Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/
"It's not the things you don't know
what gets you into trouble.

"It's the things you do know
that just ain't so."
Will Rogers

Gene Nygaard wrote:
Up there in the Great White North, they use those dinky little
"litres" where it takes 4.54609 of them to make a gallon, rather than
the man-sized liters we have, which only take 3.785411784 to make a
gallon. ;-)

I suspect it's not the litre which is different, but the gallon which is
different. The British Imperial Gallon occupies 277.4 in^3, while the
gallon you're thinking of occupies 231 in^3.

What's your opinion of converting US speedometers from miles/hr to
furlongs/fortnight?

73, AC6XG

Jim Kelley wrote:
"Quantities in the colored areas [ounce, pound, ton] are not mass units
but are often used as such.

What is the mass of a banana slug in slugs?
--
73, Cecil, W5DXP

Cecil Moore wrote:

Jim Kelley wrote:
"Quantities in the colored areas [ounce, pound, ton] are not mass units
but are often used as such.

What is the mass of a banana slug in slugs?

Ask somebody at UC Santa Cruz. ;-)

73, ac6xg

You are equating pound and POUNDAL ['pound mass']. They are two
different things.

----------------------------------------

Sears and Zemansky, 1956, Table 5-1, page 77

Systems of units Force Mass Acceleration
Engineering pound Slug ft/sec^2
mks newton kilogram m/sec^2
cgs dyne gram cm/sec^2
----------------------------------------

"One standard pound, by definition, is a body of mass 0.4535924277 kg."

"Since the weight of a body is a force, it must be expressed in units of
force. Thus in the engineering system weight is expressed in POUNDS; in
the mks system, in Newtons; and in the cgs system, in dynes."

Unless you disagree with Newton's Second Law, F=ma, Force [pounds] and
mass [slugs] are related by acceleration [of gravity, for example].

So, my weight [240 pounds] = my mass [7.45 slugs]*[gravity of 32.2
ft/sec^2].
-----------------------------------------
If you want to argue, go ahead. I cited a source as you asked. Now you
choose to disagree with that source.

My final comment: Does a newton[force] = a kilogram[mass]??
--------------

Conclusion:

Force = pounds, or newtons, or dynes.
Mass = Slug, or kilogram, or gram
Acceleration = ft/sec^2, or m/sec^2, or cm/sec^2
----------------------------------------
Don't be so everbearing! It does not become you or enhance you statements.

Gene Nygaard wrote:

On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark
wrote:

On Thu, 25 Sep 2003 06:45:29 -0400, wrote:

Let's just all go metric. The only really confusing measure
there seems to be the definition of the litre.

...Keith

Hi Keith,

You mean liter? ;-)

It has to be litre so that it can rhyme with metre.

Up there in the Great White North, they use those dinky little
"litres" where it takes 4.54609 of them to make a gallon, rather than
the man-sized liters we have, which only take 3.785411784 to make a
gallon. ;-)

Unless, of course, you are talking about blueberries, where we use an
inbetween liter where it takes 4.40488377086 liters to make a gallon
(which we actually don't use much under that name any more, though we
do still use its quart and pint subdivisions).

We also have the Texas sized foot of 12.789 inches (legal for
surveying only in Quebec, they say).

But it seems that in the great country to the south there are
also two definitions for the foot: 0.3048 meter and
1200/3937 meter. When I buy a tape measure made in the U.S.A.
am I getting long feet or short feet?

....Keith

On Thu, 25 Sep 2003 19:11:42 -0400, wrote:

Gene Nygaard wrote:

On Thu, 25 Sep 2003 15:58:11 GMT, Richard Clark
wrote:

On Thu, 25 Sep 2003 06:45:29 -0400, wrote:

Let's just all go metric. The only really confusing measure
there seems to be the definition of the litre.

...Keith

Hi Keith,

You mean liter? ;-)

It has to be litre so that it can rhyme with metre.

Up there in the Great White North, they use those dinky little
"litres" where it takes 4.54609 of them to make a gallon, rather than
the man-sized liters we have, which only take 3.785411784 to make a
gallon. ;-)

Unless, of course, you are talking about blueberries, where we use an
inbetween liter where it takes 4.40488377086 liters to make a gallon
(which we actually don't use much under that name any more, though we
do still use its quart and pint subdivisions).

We also have the Texas sized foot of 12.789 inches (legal for
surveying only in Quebec, they say).

Interestingly enough, Thomas Jefferson used Isaac Newton's
measurements of the length of a seconds pendulum at various latitudes
in terms of these feet, the royal foot of Paris, to calculate how long
his foot would be in terms of the English feet then in use, when he
proposed a decimal system based on the foot in 1790, before the metric
system had been invented. In Jefferson's system, a metre would have
been a cubic inch (0.001 cubic foot), and a metre of cool water would
have a mass of 1 ounce (0.1 pound), and an ounce of 11/12 silver would
have been a dollar.
Plan for establishing uniformity in the Coinage, Weights, and Measures
of the United States.
http://ourworld.compuserve.com/homep...jeff.htm#from2

Some surveys in the United States (Lousiana) were originally done in
these feet also, with lengths and areas in arpents. Some land grants
in southwestern states were in terms of varas of various sizes, with
areas expressed in labors and leagues.

But it seems that in the great country to the south there are
also two definitions for the foot: 0.3048 meter and
1200/3937 meter. When I buy a tape measure made in the U.S.A.
am I getting long feet or short feet?

The short ones, of course. The same document I cited before, the
Federal Register notice which is the U.S. law redefining the yard as
0.9144 m and the pound as 0.45359237 kg spells out the limited
surveying purposes for which the old definition would continue to be
used.
http://www.ngs.noaa.gov/PUBS_LIB/Fed...doc59-5442.pdf
http://gssp.wva.net/html.common/refine.pdf

Seriously, you are buying a lot better quality tape measures than I
have ever used, if you expect them to be accurate to that 2 parts per
million difference. Are any tape measures that good? You will, of
course, have to be making temperature corrections as well.

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/

On Thu, 25 Sep 2003 11:51:47 -0700, Jim Kelley
wrote:

"Fundamentals of Physics", Haliday and Resnick, Second Edition, 1981

Appendix F, Conversion Factors

Mass

"Quantities in the colored areas [ounce, pound, ton] are not mass units
but are often used as such. When we write, for example 1 kg "=" 2.205
lb this means that a kilogram is a _mass_ that _weighs_ 2.205 pounds
under standard condition of gravity (g = 9.80665 m/s^2)."

The units dyne, Newton, pound, and poundal are listed elsewhere in
Appendix F as units of force.

73, AC6XG

Apparently Halliday and Resnick were a lot smarter a couple of decades
earlier, when they were only a little past their prime:

Robert Resnick and David Halliday, Physics For Students of Science and
Engineering, John Wiley & Sons, 1960.

[page 10]

Legally, the pound is a unit of mass. But in engineering
practice the pound is treated as a unit of force or weight.
This has given rise to the terms pound-mass and pound-
force. The pound mass is a body of mass 0.45359237
kg; no standard block of metal is preserved as the pound-
mass, but like the yard it is defined in terms of the mks
standard. The pound-force is the force that gives a
standard pound an acceleration equal to the standard
acceleration of gravity, 32.1740 ft/sec².

So what are you going to believe? The main text of a book which
actually uses pounds? Or something hidden away in an appendix (which
the authors likely assinged some secretary to put together for them),
in a book which doesn't even use pounds?

Now go back in the book you have, and take a look at some of the
earlier stuff in it.

[page 356]

In the engineering system the unit of heat is the
British thermal unit (Btu), which is defined as the
heat necessary to raise the temperature of one
pound of water from 63 to 64°F.

How much water? You don't think that this is the amount of water that
exerts a certain amount of force due to gravity, do you?

What about when they give specific heat capacity in units expressed in
as Btu/lb °F in this book? What the hell do you suppose those units
in the denominator are? The corresponding metric unit in their book
are "cal/g°C"; does that give you any clues?

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/

On Thu, 25 Sep 2003 20:06:37 GMT, Dave Shrader
wrote:

You are equating pound and POUNDAL ['pound mass']. They are two
different things.

Good grief! Go find a dictionary, or a physics book published before
1940 (and a number of them published later as well, it's just that for
the 60 years before then it's a virtual certaintly that you'll see
poundals used in these textbooks).

Poundals are unit of force. Not units of mass. A poundal is not a
pound mass; it is not mass at all. A poundal is also not a pound
force. In fact, it takes 32.16 pdl or 32.1740... pdl or 32.175 pdl,
or something in that neighborhood, to make a pound force. The exact
number will depend on how you choose to define a pound force, which
doesn't even have an official definition. The de facto standard today
is to define it so that it has the same relationship to a pound as a
kilogram force has to a kilogram. Or, that a pound force has the same
relationship to a kilogram force as a pound has to a kilogram.
That's what I'll use for any other related numbers below.

----------------------------------------

Sears and Zemansky, 1956, Table 5-1, page 77

Systems of units Force Mass Acceleration
Engineering pound Slug ft/sec^2
mks newton kilogram m/sec^2
cgs dyne gram cm/sec^2
----------------------------------------

Still too ****ing dumb to see any adjective there, identifying a
particular subset of English units? Even after it has been
specifically pointed out to you?

You know, I was tempted to give you the benefit of the doubt, and
assume that this had been sent before you had a chance to read my
discussion of the 1970 edition of Sears and Zemansky. But then I
double checked, not only that it graphically appeared to below that
message on my newsreader, but also that your message did indeed in
References the message ID of that one in which I discussed the 1970
ecition.

"One standard pound, by definition, is a body of mass 0.4535924277 kg."

I told you the number would be different, didn't I--but that S&Z would
not lie to you about the fact that pounds are units of mass.

"Since the weight of a body is a force, it must be expressed in units of
force. Thus in the engineering system weight is expressed in POUNDS; in
the mks system, in Newtons; and in the cgs system, in dynes."

Do you see any adjective modifying "system" here, in each of the three
times it is used?

Does the existence of a kilogram force prove that kilograms are not
units of mass? No. Does the existence of a pound force prove that
pounds are not units of mass? No.

Do you know that what they call the "engineering" system is, like SI,
a coherent system of units, as that term is used in the jargon of
metrology? Do you know what that means? It means that there is only
one unit for each different quantity, and that that unit is a unitary
combination of the base units.

Do you know the implications of that? That means that this system
which they identify as the "engineering system" doesn't have any pints
or gallons, no Btu or horsepower, no ounces or inches or miles or
furlongs or fortnights. That's the only system that includes
slugs--the one that doesn't have a whole lot of our commonly used
units.

What's more, that's only one of several such systems. Some of the
others include the absolute fps system (the one with pounds for mass
and poundals for force), the gravitational inch-pound-second system
(no slugs here either; the unit of mass in this system, equal to 1
lbf·s²/in, or about the weight (a synonym for mass in this case, of
course) of the heaviest NFL linemen today, is probably most often used
without a name, though some NASA engineers have called it a "slinch").

Unless you disagree with Newton's Second Law, F=ma, Force [pounds] and
mass [slugs] are related by acceleration [of gravity, for example].

You can just as easily say that force [poundals] and mass [pounds] are
related by the acceleration [ft/s²]. It's every bit as true--and that
system has been around a lot longer than the one with slugs.

Furthermore, Newton didn't use symbol to express this, and he only
said that force is proportional to mass times the acceleration of
gravity. Symbolically, that's F = kma. Using this more general form,
you can use any units you want to for each of these quantities, as
long as you make the constant k fit with them. That's what must be
done in the system generally called the English "engineering" system
of units (Sears and Zemansky are idiots who aren't even able to
understand the distinction between the system identified by this term
in normal usage by most other people, and the one they call by this
name which everyone else calls the "gravitational" or "gravimetric"
fps system of units). In what everyone else calls the engineering
system of units, pounds are used for mass and pounds force for force,
and for Newton's Second Law we have F = kma where k = 0.03108095 =
1/32.1740.

So, my weight [240 pounds] = my mass [7.45 slugs]*[gravity of 32.2
ft/sec^2].
-----------------------------------------
If you want to argue, go ahead. I cited a source as you asked. Now you
choose to disagree with that source.

Go read my quotes from NIST and from ASTM on the subject of human body
weight in my longest reply to Richard Clark.

My final comment: Does a newton[force] = a kilogram[mass]??

No. The numbers won't even be the same, unless you happen to be some
place outside this world where the local acceleration of free fall is
pretty close to 1 m/s².

Furthermore, a kilogram force doesn't equal a kilogram either, not
even if you call it by its other name, the kilopond. They measure
different quantities. On earth, the numbers associated with each
might be close to each other if the force you are measuring is the
force due to gravity--but that doesn't make them "equal."

Now here's something else for you to chew on. Just to show that there
have been people using metric units who have been bound and determined
to show that they can be every bit as silly as those using English
units, look up a unit of mass known variously as the hyl, or by the
German acronym TME, or as the mug, which is derived from another of
its names, the "metric slug." This is the mass which a kilogram of
force will accelerate at a rate of 1 m/s².

In that system, the base units are the meter for length, the second
for time, and the kilogram for force, with the hyl as the coherent,
derived unit of mass.

Note that in that system, kilograms are never units of mass. Exactly
the same as that system which Sears and Zemansky mislabel the
"engineering" system, a similar limited subset of the English units
rather than of the metric units, in which subset the pound is not used
as a unit of mass.

Granted, that system probably never did see extensive use, and I
haven't seen it used at all recently. But it's mere existence shoots
all kinds of holes in your theories related to Newton's second law,
and all the different names that the mass unit in this system has been
given are clear evidence that it has been independently reinvented
many times over.

The existence of the hyl does not prove that kilograms are not units
of mass. The existence of the slug does not prove that pounds are not
units of mass.

--------------

Conclusion:

Force = pounds, or newtons, or dynes.
Mass = Slug, or kilogram, or gram
Acceleration = ft/sec^2, or m/sec^2, or cm/sec^2
----------------------------------------
Don't be so everbearing! It does not become you or enhance you statements.

It's a tradeoff I'm willing to accept as the price of getting the
message through some awfully thick skulls. After all, there are a lot
of dearly held memories of favorite teachers out there, and it's
awfully hard for anyone to admit that some favorite might actually
have led them astray.

For example, what about all those pounds you see in the grocery store?
You've been ignoring them for a long time, haven't you? Or are you
really so god-awful stupid as to think that when we buy and sell goods
by "weight" we'd want to measure some quantity that varies with
location?

PHASE II

Now, let's move on to Phase II of our examination of Sears and
Zemansky. Once again, I'll use the 1970 edition. Feel free to jump
in as show us that they said essentially the same thing in 1956.
Francis Weston Sears and Mark W. Zemansky, University Physics,
Addison-Wesley, 4th ed., 1970.

[page 228 (formula changed to one line)]:

If the system undergoes a temperature change dt,
the specific heat capacity c of the system is defined
as the ratio of the heat dQ to the product of the mass
m and temperature change dt; thus

c = dQ/(m dt)

The specific heat capacity of water can be taken
to be 1 cal g-1 (C°)-1 or 1 Btu lb-1 (F°)-1 for most
practical purposes.

Tell me, what exactly does "lb" mean in this quote?
Hints:
1. Look at what they tell you the denominator is in words. That would
the first quantity identified as part of the "product."
2. Look at the unit in the same position as "lb" in the calories
formula.

[page 230]

Mechanical engineers frequently use the British
thermal unit (Btu), defined as the quantity of heat
required to raise the temperature of 1 lb (mass) of
water from 63°F to 64°F. The following relations hold:

1 Btu = 778.3 ft lb = 252.0 cal = 1055 J.

How much water?

[page 232]

The quantity of heat per unit mass that must be
supplied to a material at its melting point to convert
it completely to a liquid at the same temperature is
called the heat of fusion of the material. The quantity
of heat per unit mass that must be supplied to a
material at its boiling point to convert it completely
to a gas a the same temperature is called the heat
of vaporization of the material. Heats of fusion and
vaporization are expressed in calories per gram, or
Btu per pound. Thus the heat of fusion of ice is
about 80 cal g^-1 or 144 Btu lb^-1. The heat of
vaporization of water (at 100°C) is 539 cal g^-1 or
970 Btu lb^-1. Some heats of fusion and
vaporization are listed in Table 16-2.

Now, it doesn't take a whole lot of genius to figure out what the
quantities are which are measured in those units with the -1
exponents, does it?

But you don't even have to guess. Sears and Zemansky come right out
and tell you. For you and some of the other slow-witted folks in this
thread, here's a hint: Look for the seventh word in each of the first
two sentences, that little word sandwiched in between the words "unit"
and "that." Did you find it?

Do you notice anything strange here? Something different from that
textbook which Keith described for us, which used "lbm" for pounds
mass and "lbf" for pounds force?

Sears and Zemansky, earlier in the book, use the word "pound" and the
symbol "lb" for units of force. But here they are using the word
"pound" and the symbol "lb" for units of mass.

I feel sorry for you if you had to learn physics from idiots like
this. But that still doesn't excuse your ignorance half a century
later; you've had lots of opportunities in the intervening years to
figure out the truth on your own.

Gene Nygaard
Time flies like an arrow;
fruit flies like a banana.